Nakamura T, Kon Y, Iwahashi H, Eguchi Y
J Bacteriol. 1983 Nov;156(2):656-62. doi: 10.1128/jb.156.2.656-662.1983.
Mutants carrying defects in cysteine synthase A or B or both were isolated from Salmonella typhimurium LT2. Parent strains were able to grow on minimal media containing sulfate, sulfite, sulfide, or thiosulfate as sulfur sources. Mutants lacking cysteine synthase B were unable to grow on thiosulfate, whereas mutants lacking cysteine synthase A grew on the four inorganic sulfur sources described above with little difference in their growth rates. Mutants lacking both cysteine synthases failed to grow on media containing any of the inorganic sulfur sources tested. Purification of cysteine synthase B resulted in the copurification of S-sulfocysteine synthase. In addition, the two activities were also cotransduced. These activities appear to be associated with the cysM gene, and this is able to be cotransducted with the cysK gene at a high frequency. From these results, it may be concluded that thiosulfate is assimilated via S-sulfocysteine exclusively with the aid of S-sulfocysteine synthase.
从鼠伤寒沙门氏菌LT2中分离出了在半胱氨酸合酶A或B或两者中存在缺陷的突变体。亲本菌株能够在含有硫酸盐、亚硫酸盐、硫化物或硫代硫酸盐作为硫源的基本培养基上生长。缺乏半胱氨酸合酶B的突变体无法在硫代硫酸盐上生长，而缺乏半胱氨酸合酶A的突变体能够在上述四种无机硫源上生长，其生长速率差异不大。缺乏两种半胱氨酸合酶的突变体无法在含有任何一种测试无机硫源的培养基上生长。半胱氨酸合酶B的纯化导致S-磺基半胱氨酸合酶的共纯化。此外，这两种活性也被共转导。这些活性似乎与cysM基因相关，并且它能够与cysK基因以高频率共转导。从这些结果可以得出结论，硫代硫酸盐仅借助S-磺基半胱氨酸合酶通过S-磺基半胱氨酸被同化。
